Oil and gas wells are often completed with an open hole in unconsolidated producing formations containing fines and sand which flow with fluids produced from the formations. The sand in the produced fluids can abrade and otherwise damage tubing, pumps, etc. and must be removed from the produced fluids. Filters, e.g. sand screens, are commonly installed in well bores and gravel packed to filter out the fines and sand in the produced fluids.
The portion of the well above the producing formation is usually lined with a steel casing. The annulus between the casing and the well bore is normally filled with cement. When a screen is placed in the producing zone, a length of blank pipe, sometimes referred to as a liner, may be connected to the top of the screen assembly and extend upward into the cased portion of the well to provide a flow path for produced fluids from the screen to the cased portion of the well. At least a portion of the annulus between the blank pipe and open hole below the casing is normally filled with cement to hold the blank pipe and screen assembly in place and block annular flow of fluids around the blank pipe.
Thus, a well completion in an open hole zone usually requires both a gravel packing operation and a cementing operation. Both of these completion operations are well known. However, these operations have typically been performed using multiple sets of equipment run into the well at different times. For example, a length of blank pipe or liner may be placed in the well and a cementing assembly may be run into the well to perform cementing of the blank pipe or liner. Then, the cementing assembly is typically removed from the well. Then, a screen may be placed in the well and a gravel packing assembly may be run into the well for gravel packing the screen. Thus, multiple trips into the well have typically been required to place the blank pipe and the screen and to gravel pack the screen and cement the blank pipe. Each trip into the well to position equipment or perform an operation requires additional time and expense.